Method and device for determining a path around a defined reference position

ABSTRACT

A path is determined in the following iterative way: An arcuate path around the reference position having a predetermined spacing is determined step-by-step. The existence of an obstacle along the arcuate path is checked. The arcuate path is lengthened as long as no obstacle is found. When an obstacle is found, the spacing is enlarged by a prescribable value and the method is continued in a new iteration with the enlarged spacing.

The invention is directed to a method and to an arrangement fordetermining a path.

Such a method and such an arrangement are known from [1]. In thisdetermination, markings are employed in order to define a path alongwhich a robot moves.

The marking of a path is involved and, thus, expensive, and is also notdesired in all areas. In particular, the demand is made of a robot thatit find its way on its own such in a space in which it had notpreviously been and about which it also has no data stored in a memoryin the form of a digital map that it can the entire space as gap-free aspossible, whereby a multiple traversal of one area of the space shouldbe kept as slight as possible.

The invention is thus based on the problem of determining a path arounda predetermined reference position, as a result whereof a simplified,cost-beneficial navigation within a space is possible without priorknowledge, and no markings are required.

The problem is solved by the method as well as by the arrangement havingthe features according to the independent patent claims.

The following steps are iteratively implemented in the method:

An arcuate path around the reference position having a predeterminedspacing is determined step-by-step;

the existence of an obstacle along the arcuate path is checked;

the arcuate path is lengthened as long as no obstacle is found;

when an obstacle is found, the spacing is enlarged by a prescribablevalue and the method is continued in a new iteration with the enlargedspacing.

The arrangement comprises a processor that is configured such that aniterative method having the following steps can be implemented:

An arcuate path around the reference position having a predeterminedspacing is determined step-by-step;

the existence of an obstacle along the arcuate path is checked;

the arcuate path is lengthened as long as no obstacle is found;

when an obstacle is found, the spacing is enlarged by a prescribablevalue and the method is continued in a new iteration with the enlargedspacing.

The invention specifies a very simple and, thus, cost-beneficialnavigation strategy for a mobile arrangement in a space. the inventioncan be advantageously utilized for steering an arrangement along theidentified path. What is achieved in this way is that, given a space inwhich the arrangement had not previously been and about which thearrangement has no information, an arrangement can cover the entirespace with a slight overlap area in a very simple and cost-beneficialway. What is to be understood as an overlap area is a part of the spacein which the path that is multiply contained in the identified path isdetermined.

It is provided in a development of the invention that the arrangement isconnected via a cable to an electrical terminal that represents thereference position. The distance is determined on the basis of the cablelength. This development established an extremely cost-beneficial and,due to an element, the cable, already contained in the power supplygiven a plurality of arrangements, cost-beneficial [sic] orientation aidfor the arrangement.

The invention can be advantageously utilized for the orientation of arobot or, too, of a vacuum cleaner.

An exemplary embodiment of the invention is shown in the drawings and isexplained in greater detail below.

Shown are:

FIGS. 1-10 sketches of a space that represent the determination of thepath by way of example;

FIG. 11 a symbolic sketch of a vacuum cleaner in plan view;

FIG. 12 a symbolic sketch of a vacuum cleaner with a processor, a memoryand a steering mechanism.

FIG. 1 shows a room 101 with walls 102 and a table 103 as an obstacle.

A vacuum cleaner 104 is connected via a cable 105 to an electricalterminal 106, a receptacle. The vacuum cleaner 104 comprises a pivotablearm 107. The arm 107 also comprises a plurality of tactile sensors 108with whose assistance an obstacle is recognized by touching the obstaclewith the arm 107.

As shown in FIG. 12, the vacuum cleaner 104 comprises a processor 1201as well as a memory 1202 that are connected to one another via a bus1203. An identified and traversed path 109 is stored in an electronicmap 1213 in the memory 1202. Every obstacle identified on the path isentered in the map 1213.

The vacuum cleaner 104 also comprises a cable drum 1204 for winding upacable 1205.

The cable 1205 is conducted out of the vacuum cleaner 104 through anopening 1206 in the housing 1207 of the vacuum cleaner 104. The cabledrum 1204 comprises a motor 1208 with which the cable drum 1204 isdriven for unwinding or, respectively, winding up the cable 1205. Thevacuum cleaner 104 also comprises a steering mechanism 1209 connected tothe bus 1203 with which the wheels 1210 of the vacuum cleaner 104 and amotor 1211 for driving the vacuum cleaner 104 are driven such that thevacuum cleaner 104 travels through a room on the above-described path.

The method described below for determining the path is implemented inthe processor 1201. Further, the vacuum cleaner 104 comprises a movablearm 1212 with a suction nozzle 1214 and a dust bag 1215 for holding thedust.

The path 109, which is symbolically shown with a line in FIG. 1, isdetermined and traversed by the vacuum cleaner in the following way.

The path 109 begins at the electrical terminal 106. The vacuum cleaner104, using the tactile sensors 108, recognizes the wall 102 as anobstacle and travels on a straight path along the wall in a prescribabledirection 110, which is indicated by an arrow 110, until a predeterminedlength of the cable 105 has been reached. A distance is determined bythe length of the cable 105.

The vacuum cleaner 104 now travels over an arcuate path around theelectrical terminal with the interval of the cable length as radiusuntil a tactile sensor 108 determines an obstacle.

The arm 107 is thereby laterally swivelled around the path 109, and thevacuum cleaner 104 vacuums the floor.

The vacuum cleaner 104 recognizes the wall 102 at the side of theelectrical terminal 106. When the wall 102 is recognized as obstacle,which is symbolically represented as rings 111 in FIG. 1, then a checkis carried out to see whether a path that was already previouslytraveled is selected given selection of the path 109 in the direction ofthe electrical terminal 106, i.e. when the interval and, thus, the cablelength are shortened.

The check ensues with reference to the stored map. 1213 in which a path109 already traveled by the vacuum cleaner 104 is stored.

In this exemplary embodiment, the vacuum cleaner 104 has detected thetable 103 as obstacle on the way to the wall lying opposite theelectrical terminal 106, this being symbolically shown with two rings112, 113 in FIG. 1.

The traversed path 109 is stored in the map 1213 in such a way that afirst sub-section of the path 109 in which an obstacle has been detectedis provided with a first marking, this being symbolically shown in theFigures with rings. A second subsection of the path 109 wherein noobstacle has been detected—referred to below as open area—is providedwith a second marking, which is symbolically shown in the Figures with arespective asterisk.

FIG. 2 shows the case that, as shown in FIG. 1, the path would lead intoan area that has already been traversed given a path selection in thedirection of the electrical terminal 106.

For this reason, the vacuum cleaner 104 travels along the wall, wherebythe cable 1205 is played out from the cable drum 1204 of the vacuumcleaner 104, as a result whereof the cable length and, thus, theinterval for a second arcuate path 202 is increased.

Until the cable length has arrived at the prescribable value for theinterval of the second arcuate path 202, the vacuum cleaner 104 travelsalong the wall 102, this being shown but a first sub-path 201 in FIG. 2.

FIG. 3 shows the situation that the vacuum cleaner 104 again encountersthe table 103, this being determined by the tactile sensors 108. Thissituation is symbolically represented by rings 301, 302, 303. The rings301, 302, 303 represent symbolically stored, first markings within thestored map 1213. The markings are stored in the form of a progression[or: draft of traverse].

A check is again carried out to see whether the table 103 can be avoidedby moving the vacuum cleaner 104 in the direction of the electricalterminal 106 without having to again travel over a path that has alreadybeen traversed. Since this is not possible in this case, the cablelength and, thus, the interval are again increased.

While the cable 105 is being ejected from the cable drum 1204 of thevacuum cleaner 104, the vacuum cleaner 104 travels over a secondsub-path 304 along the table 103.

After reaching the end point of the interval prescribed by the cablelength, the vacuum cleaner 104 travels along another arcuate path 305until the tactile sensors 108 again encounter the wall 102 of the room101, this being symbolically represented by two further rings 306, 307.

FIG. 4 shows the situation that, by shortening the interval, an area ofthe room 101 that has not yet been traversed by the vacuum cleaner 104is covered in the direction of the electrical terminal 106. This area issymbolically represented by two rings 401, 402 as well as by a thirdsub-path 403.

The vacuum cleaner 104 travels in the direction of the electricalterminal 106 until it encounters an area that was already previouslycovered by the vacuum cleaner 104, this being determined by comparisonwith the map 1213 stored in the memory 1202.

FIG. 5 shows a fourth sub-path 501 that the vacuum cleaner 104 travelsalong the wall 102 of the room 101 with what is again an increased cablelength, as presented above.

Another arcuate path 502 is traversed by the vacuum cleaner 104 until itagain encounters the table 103. This situation is symbolicallyrepresented by two further rings 503 and 504.

The vacuum cleaner 104 travels a fifth sub-path 505 along the table 103in order to subsequently again [. . . ] a further arcuate path 506around the table until it arrives at the already marked area of thetable, an end point 507.

After traveling over a sixth sub-path 506 with lengthening of the cable,the vacuum cleaner 104 travels over another arcuate path 508 until itencounters a second wall 102. This situation is symbolized by threefurther rings 509, 510, 511. The vacuum cleaner continues to travelalong the further arcuate path 508 until it encounters a third wall 102,symbolized by two rings 512 and 513.

Three open areas arise in this way, a first open area 514, a second openarea 515 and a third open area 516 that are respectively identified withasterisks.

FIG. 6 shows the traversal of the third open area 516 on the part of thevacuum cleaner according to the above-described rules along furthersub-paths 601, 602 and further arcuate paths 603, 604.

Consulting the map 1213, the vacuum cleaner 104 determines that it hascovered the entire third open area 516 since the vacuum cleaner 104 canno longer travel over any area in the third open area 516 in which ithas not already been.

The vacuum cleaner 104 now targets an area that is identified in the map1213 as having not yet been traversed, i.e. the first open area 514 andthe second open area 515. The vacuum cleaner 104, selected the firstopen area 514 and approaches it along an intermediate path 700.

The path 109 is stored in the map 1213 in the form of a tree structure,whereby an arcuate path is modelled in the form of a node 701, 702, 703,704, 705, 706, 707 within the tree structure. An attribute isrespectively allocated to the node K, a first attribute (symbolized by afilled-in circle 701, 702, 704, 705, 706) that indicates that thearcuate path does not adjoin an open area, or a second attribute(symbolized by an empty circle 703, 707) that indicates that the arcuatepath adjoins an open area (see FIG. 7).

The vacuum cleaner travels toward the first open region 514 and travelsover the first open area according to the above-described procedurealong a further sub-path 801 (see FIG. 8) and a further arcuate path802.

FIG. 9 shows the vacuum cleaner 104 after the complete first open area514 and a part of the second open area 515 have been covered alongfurther sub-paths 901 and 902 as well as further arcuate paths 903, 904.

FIG. 10 shows the vacuum cleaner 104 after the complete room 101 hasbeen covered along further sub-paths 1001, 1002 as well as a furtherarcuate path 1003.

FIG. 11 shows the vacuum cleaner 104 in plan view. The vacuum cleanercleans the floor of the room 101 in that it moves a nozzle 1101, whichis contained in an arm 1103, essentially perpendicular to the mainmoving direction (symbolized by an arrow 1105) of the vacuum cleaner104, i.e. basically executes a wiping motion, symbolized by an arcuatedouble arrow 1104. A housing 1102 that travels along the main movingdirection comprises wheels 1106, 1107, 1108 that are at least partlydriven by a motor (not shown).

The cable is conducted out of the housing 1102 through an opening 1109.

Some alternatives to the above-described exemplary embodiment areindicated below:

A qualitative location determination can ensue by measuring the lengthof the cable or, too, by employing further sensors for measuring thedistance of the vacuum cleaner from the electrical terminal, generally afixed reference point.

The further sensors can ensue [sic] according, for example, to theprinciple of an acoustic transit time measurement, whereby the sound isoutput by a transmitter of the vacuum cleaner. The result of the transittime measurement is sent back to the vacuum cleaner, for example with anoptical signal, radio signal or directly via a signal transmitted overthe cable.

As described above, the room as well as the covered area are stored inthe map 1213 in the form of a tree structure. One strategy forapproaching the areas that are still respectively open ensues uponanalysis of the attributes that are allocated to the nodes of the tree,whereby a distance particular is also respectively allocated to thenodes that indicates how far the respective, further arcuate path isfrom the electrical terminal.

Possible strategies are:

“Depth first”:

In this strategy, the nodes to which the first attribute is allocatedare approached in that sequence that the node whose appertaining,arcuate path is at the greatest distance from the electrical terminal isrespectively selected.

“Width first”:

In this strategy, the nodes to which the first attribute is allocatedare approached in the sequence that the node whose appertaining arcuatepath lies closest to the electrical terminal is respectively selected.

“Best first”:

In this strategy, the nodes to which the first attribute is allocatedare approached in the sequence that the node that is optimum in view ofa prescribable criterion is respectively selected.

The following publication has been cited in this document:

[1] J. Borenstein, Navigating mobile robots: systems and techniques, A.K. Peters Ltd., ISBN 1-56881-058-X, pages 141-151, 1996.

What is claimed is:
 1. A method for computer-supported determination ofa path in a proximity of a predetermined reference position, comprisingthe iteratively repeated steps of: determining step-by-step an arcuatepath in a proximity of said reference position having a predeterminedspacing; checking for an existence of an obstacle along said arcuatepath; lengthening said arcuate path if no obstacle is found; enlargingsaid spacing, when an obstacle is found, by a prescribable value; andcontinuing said method in a new iteration with said enlarged spacing. 2.The method according to claim 1, further comprising the steps of:storing an electronic map of said path; and entering every identifiedobstacle into said electronic map.
 3. The method according to claim 2,wherein said map describes an identified path in the form of aprogression.
 4. The method according to claim 1, further comprising thesteps of: checking, in every iteration after detecting an obstacle, asto whether an already-contained path that is already contained in anidentified path would be determined given a shortening of an interval;determining an increased-interval path with an increased interval ifsaid determined path is already contained; and determining ashortened-interval path with a shortened interval if said determinationpath is not already contained in a new iteration.
 5. The methodaccording to claim 1, wherein said obstacle is a wall of said determinedpath.
 6. The method according to claim 1, further comprising the step ofdetermining an obstacle path along said obstacle given a lengthening ofan interval.
 7. The method according to claim 1, wherein said referenceposition is an electrical terminal.
 8. The method according to claim 7,further comprising the step of: steering an arrangement along anidentified path.
 9. The method according to claim 8, wherein saidarrangement is connected to said electrical terminal via a cable. 10.The method according to claim 9, wherein said cable length is designedto be variable and an interval is determined based on said cable length.11. A robot that utilizes the method according to claim
 8. 12. A vacuumcleaner that utilizes the method according to claim
 8. 13. Anarrangement for determining a path in a proximity of a predeterminedreference position, comprising: a processor that is configured toimplement the following steps in an iterative manner: determiningstep-by-step an arcuate path in a proximity of said reference positionhaving a predetermined spacing; checking for an existence of an obstaclealong the arcuate path is checked; lengthening said arcuate path if noobstacle is found; enlarging said spacing, when an obstacle is found, bya prescribable value; and implementing a continuation of said steps in anew iteration with said enlarged spacing.
 14. The arrangement accordingto claim 13 comprising at least one sensor for determining an obstacle.15. The arrangement according to claim 13, comprising a memory in whichan electronic map of a path can be stored, every identified obstaclebeing entered within said map.
 16. The arrangement according to claim15, wherein said processor is configured to implement said mapdescribing an identified path in a form of a progression.
 17. Thearrangement according to claim 13 wherein said processor is configuredto: check, in every iteration after detecting an obstacle, as to whetheran already contained path that is already contained in an identifiedpath would be determined given a shortening of an interval; determine anincreased-interval path with an increased interval if said determinedpath is already contained; and determine a shortened-interval path witha shortened interval if said determination path is not already containedin a new iteration.
 18. The arrangement according to claim 13, whereinsaid obstacle is a wall of said identified path.
 19. The arrangementaccording to claim 13 wherein said processor is configured to determinea path along an obstacle given a lengthening of an interval.
 20. Thearrangement according to claim 13, wherein said reference position is anelectrical terminal.
 21. The arrangement according to claim 20, furthercomprising a steering mechanism with which said arrangement is steeredalong an identified path.
 22. The arrangement according to claim 21,further comprising a cable by which said arrangement is connected tosaid electrical terminal.
 23. The arrangement according to claim 22,wherein said cable length is designed variable and said interval can bedetermined based on said cable length.
 24. The arrangement according toclaim 21, wherein said arrangement is a robot.
 25. The arrangementaccording claim 21, wherein said arrangement is a vacuum cleaner.